Bipolar Hip Prosthesis Research Articles

Short-term results of revision THA after bipolar hip prosthesis

Short-term results of revision THA after bipolar hip prosthesis

The cost effectiveness between osteosynthesis and bipolar hip prosthesis replacement for femoral neck fracture

The cost effectiveness between osteosynthesis and bipolar hip prosthesis replacement for femoral neck fracture

Wear of bipolar hip prostheses

A method was developed to take radiographs showing the inner articulation of bipolar hip prostheses. By this method, wear was measured in 68 hips whose inner head diameter was 22 mm. Average annual wear rate was 0.17 mm. Osteolysis was observed in 25 hips (37%) and there was no difference between the annual wear rate of hips with and without osteolysis. Studying 19 retrieved prostheses, abrasion of the rim was deeper in hips with osteolysis than those without it. Wear rate of the inner articulation in bipolar hip prosthesis is much larger than that in Charnley's prosthesis, as linear penetration into the articulation surface reduces the motion range of the inner articulation and this increases impingement and advances rim abrasion.

Ｂｉｐｏｌａｒ型人工骨頭置換術後にｉｎｎｅｒ ｈｅａｄが脱臼した一例

We experienced one case of dislocation of the inner head in biporal hip prosthesis caused by the wear of the HDP liner. The case, a 82 year-old woman with left femoral neck fracture was treated with biporal hip prosthesis, without self-centering mechanism, approximately 11 years ago. She had severe pain in her left hip while sitting down on her heels, and was unable to walk. Roentogenogram of the hip revealed extreme varus position of the outer head and dislocation of the inner head in bipolar hip prosthesis. Surgical exploration revealed the outer head that was fixed in the varus position, hyperplastic granulation in acetabulum, and manifest wearing of all inner HDP liners. This suggested that the wear occurred due to impingement between the stem neck and outer head fixed in the varus position. In conclusion, we should follow-up carefully after operation for a long period of time, and help the patient resume proper daily activities.

Failed hip prostheses in hemodialysis patients. Amyloid deposition at the bone-implant interface in 4 cases.

4 hemodialysis patients with failed bipolar hip prostheses underwent 6 revision arthroplasties. Their average age was 55 years, the average duration of hemodialysis was 14 years and the average interval from the primary arthroplasty to revision was 7 years. The interface membranes revealed amyloid deposits in all specimens. There were few polyethylene wear particles, and cement debris or foreign body reactions were rare. It appears that amyloid may cause osteolysis and early prosthetic loosening.

FEMORAL COMPONENT WEAR IN RETRIEVED HIP PROSTHESES

We retrieved 159 femoral heads at revision surgery to determine changes in surface configuration. Macroscopic wear of the head was observed in three bipolar hip prostheses as a result of three-body wear. There was a considerable change in surface roughness in the internal articulation of bipolar hip prostheses. Roughness in alumina heads was almost the same as that in new cobalt-chromium heads. The annual linear wear rate of polyethylene cups with alumina heads was less than that of cups with cobalt-chromium alloy heads. Polyethylene wear was increased in the prostheses which had increased roughness of the head.

Large amounts of polyethylene debris in the interface tissue surrounding bipolar endoprostheses: Comparison to total hip prostheses

A histologic and biochemical comparison of interface membranes around femoral components of bipolar endoprostheses (n = 17) and total hip prostheses (n = 17) inserted without cement was conducted. The patients' profiles were similar in both groups with respect to age, sex, primary diagnosis, weight, and the interval between primary and revision arthroplasty. Macroscopically, marked circumferential abrasion of the polyethylene insert in the retrieved bipolar cups was noted. Histologic analysis revealed significantly larger amounts of polyethylene debris in the bipolar group. The membranes from the bipolar group also produced significantly greater amounts of prostaglandin E 2 ( P <.05). The inflammatory membranes associated with large amounts of polyethylene debris may have contributed to aseptic loosening and osteolysis in patients with a bipolar hip prosthesis.

Retrieval analysis of orthopaedic implants. Tissue reactions around a hydroxyapatite coated hip prosthesis

For the evaluation of newly developed orthopaedic implantations, it is of utmost importance to collect all available information with respect to the behaviour of the implant. Retrieval analysis of well-functioning implants (post-mortem) and of failures (during revision) may give very valuable information with respect to short term reactions of the organism to the implant.In this case, bone reactions were studied around a titanium, hydroxyapatite (HA) coated Osteonics bipolar hip prosthesis, which was revised for severe mid thigh pain four years after implantation. Scarce remnants of a coating-like material on the surface of the prosthesis were found after inspection of the retrieved prosthesis using a dissecting microscope. Histology of these remnants and of the bony side of the bone-HA interface, failed to reveal any remnants of a HA coating. Trabecular bone which closely followed the contour of the prosthesis was found at the bone-prosthesis interface. Facing the prosthesis, this trabecular bone was mainly immature callous bone. At other locations, where mineralized bone faced the prosthesis, many small dark titanium wear particles were found. Similar particles were found in macrophages in the intertrabecular medullary space. Polyethylene wear particles were specifically located in macrophages in a soft tissue interface at more distal levels along the stem of the prosthesis.Although the observations presented in this case cannot be generalized, it clearly shows that the HA coating layer had completely disappeared after four years. More detailed retrieval studies and longer clinical follow-up studies are needed before a final evaluation of the behaviour of HA coatings and long term fixation of HA-coated prostheses can be made.

Ｂｉｐｏｌａ型人工骨頭のＰｏｌｙｔｈｙｌｅｎｅ摩擦によりＬｏｏｓｅｎｉｎｇが生じたと思われる一例

Ｂｉｐｏｌａ型人工骨頭のＰｏｌｙｔｈｙｌｅｎｅ摩擦によりＬｏｏｓｅｎｉｎｇが生じたと思われる一例

Tissue reactions around a hydroxyapatite-coated hip prosthesis: Case report of a retrieved specimen

Bone reactions were studied around a titanium, hydroxyapatite (HA)-coated Osteonics (Allendale, NJ) bipolar hip prosthesis, which was revised for severe midthigh pain 4 years after implantation. Inspection of the retrieved prosthesis using a dissecting microscope revealed scarce remnants of a coating-like material on the surface of the prosthesis; however, histology of this layer and histology of the bony side of the bone—HA interface failed to reveal any remnants of an HA coating. The interface was covered predominantly by trabecular bone, which closely followed the contour of the prosthesis, and was partly woven nonmineralized bone. At locations where mineralized bone faced the prosthesis, many small dark titanium wear particles were found. Similar particles were found in macrophages in the intertrabecular medullary space. Polyethylene wear particles were specifically located in macrophages in a soft tissue interface at more distal levels along the stem of the prosthesis. Although the observations presented in this case cannot be generalized, it clearly shows that the HA coating layer had completely disappeared after 4 years. More detailed retrieval studies and longer clinical follow-up studies are needed before a final evaluation of the behavior of HA coatings and long-term fixation of HA-coated prostheses can be made.

Bipolar Hip Prosthesis for Metastatic Tumor in Proximal Femur

Bipolar Hip Prosthesis for Metastatic Tumor in Proximal Femur

人工骨頭置換術後のステム周囲の骨塩定量法について ＯＭＮＩＦＩＴとＯＭＮＩＦＬＥＸの術後

Bone mineral densities (BMDs) around the stem of bipolar hip prostheses (OMNIFLEX or OMNIFIT) were measured in 41 hips of 33 patients by dual energy x-ray absorptiometry.Among 19 cases of OMNIFLEX (average 14 months after surgery) BMDs were higher in patients 1 year and over affter surgery than in those less than 1 year. The results suggest that active bone formation occurs around the stem about 1 year after surgery.Among 22 cases of OMNIFIT (average 45 months after surgery) no difference was found between BMDs of patients over 3 years after surgery and those less than 3 years which implies that the bone around the stem was already balanced before 3 years after surgery. The tip of the stem showed the highest BMD.

Bipolar Prosthetic Replacement for the Treatment of Avascular Necrosis of the Femoral Head

Eighty-three hips in 66 patients with nontraumatic avascular necrosis of the femoral head (ANFH) showing evidence of severe collapse or secondary osteoarthritic changes were treated with surgical implantation of bipolar hip prostheses either with or without cement fixation of femoral stems. The cases were observed for more than three years (range, three to ten years seven months; average, five years seven months) and assessed in terms of functional and roentgenographic results. These data were compared with the results of classic hemiarthroplasties using fixed head prostheses (Austin-Moore-type with curved or straight stem) that were performed at the authors' institutions before 1980. The results confirm that the clinical outcome is improved with use of the bipolar prosthesis. Satisfactory results (a score of 80 or greater on a hip function scoring system proposed by the Japanese Orthopaedic Association) were maintained throughout the follow-up period in most cases (71 of 83 hips) with the bipolar prosthetic replacements. In a group of patients with unsatisfactory results (12 hips), proximal migration of prosthetic head was seen in two cases. The incidence of proximal migration of bipolar heads, including those exhibiting minimal movement, was significantly lower when compared with that observed in an Austin-Moore-type head-fixed prosthesis group (7/83 versus 12/19) during a comparable postoperative follow-up period. It is noteworthy that the proximal migration of the bipolar head was not progressive, and, in most cases observed more than five years, the cartilaginous spaces of acetabulum were preserved, whereas in the Austin-Moore-replaced group, the migration was evident and progression occurred within three years of surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

The function of bipolar hip prostheses--a laboratory study using cadaveric acetabula.

Cadaveric acetabula were mounted in a hip simulator and the friction developed in each during articulation with a series of metal femoral head prostheses of differing sizes was measured. In a separate study, assembled Hastings bipolar hip prostheses were subjected to weight-bearing forces in the same acetabula and their self-righting mechanism was observed. The self-righting mechanism was found to function efficiently, in most cases overcoming the combined friction of the inner and outer articulations of the Hastings hip. However, during motion in the hip simulator a wide variation of friction was observed between different acetabula and within the same acetabulum with differing head size. In several cases this acetabular friction was found to be less than the friction in the inner articulation of the Hastings bipolar hip prosthesis, and this may explain some cases of reported failure of biarticular function.

Assessment of the deformation of the Bateman bipolar hip prosthesis inner bearing due to moisture absorption and creep

The mechanism of inner bearing stiffness of bipolar hip prostheses has been investigated. The Ultra-high Molecular Weight Polyethylene (UHMWPE) component of the Bateman bipolar hip prosthesis has been subjected to a series of static and dynamic tests to assess water absorption and creep. Although deformation of the UHMWPE occurred, this did not produce an increased resistance to movement in the inner bearing.

Motion of the bipolar hip prosthesis components. Friction studied in cadavers.

It has been postulated that most hip motion occurs at the inner bearing in bipolar hip prosthesis. However, radiography and cineradiography analyses have shown that the inner bearing is not always the primary articulation. We studied the frictional behavior of bipolar prosthesis and Austin-Moore prostheses and the motion of the bipolar prosthesis using a pendulum apparatus. The primary articulation was altered according to the amount of loading. When a load of 10 kg was applied to the joint, motion occurred at both bearings with friction coefficients 0.061 at the inner bearing and 0.026 at the outer bearing. With loads of over 20 kg, the outer bearing was the primary articulation. The inner bearing was the dominant articulation only when the acetabular cartilage had been removed. Our results suggest that the motion of bipolar prostheses occurs mainly at the outer bearing during normal walking, and that this prosthesis cannot be expected to reduce wear of articular cartilage.

Motion of the bipolar hip prosthesis components

Motion of the bipolar hip prosthesis components

Current Topics in the Radiology of Joint Replacement Surgery

Several methods of total hip joint replacement are currently used. Radiographic appearances after cemented, bone ingrowth, press-fit, and bipolar hip prostheses are reviewed. The roles of nuclear medicine and arthrographic procedures for identifying complications are discussed. Total knee prostheses and, in particular, complications related to the patellar component are described.

骨セメントで固定された人工股関節の再置換術における大腿骨側の問題点

The cemented stems of two cases were revised with cementless stems of bipolar hip prosthesis. In one patient, the femoral shaft was perforated by the drill. In another patient, a fracture of upper medial site of the femoral shaft was recognized by postoperative roentgenogram. The fracture was due to unremoved bone cement conecting to the lateral part of inner surface of the femoral canal. Prevention of these complications needs meticulous attentions. For example, preparation of operative instruments, and the careful intraoperative procedure.

Fractures of the Polyethylene Bearing Insert in Bateman Bipolar Hip Prostheses

Six cases of fractures of the polyethylene bearing insert of Bateman bipolar hip prostheses were observed in three patients at four to eight years after implantation. Three fractured prostheses were salvaged by replacement with new bearing inserts. In three patients, excessive acetabular cartilage wear was the indication for revision to total hip arthroplasty. Although dislocation and component disassembly have been reported as complications of the Bateman and other bipolar prostheses, fractures of the polyethylene bearing insert seems not to have been previously reported. The presumed mechanism of failure is cyclic loading of a femoral cup that is tipped into varus alignment. This concentrates stress on the weakest part of the polyethylene insert--the deep circumferential groove that joins the leaflets to the main body of the insert. Obesity and overuse were associated factors in this rare complication.